First attempt at using timing light on 65 Cutlass

[dingusboy]

Does anyone know where to get good instructions on the net regarding using a timing light to adjust the timing on my Cutlass? I'm fairly mechanical, but have never worked on cars. I want to learn from those who know on this site. Any instructions on the net with photos would be great. I want to learn all basic tune up skills before I attempt installing a Pertronix Dist.

[Olds64]

Didn't the timing light come with instructions? I don't know of a good website with pics, but we could definitely tell you how to use one. It is a simple tool to use. Essentially, all you do is hook it up and pull the trigger while the engine is running. Then you look at the timing mark in relation to the marks on the block to set the timing. It helps if you mark the timing tab and harmonic balancer with white paint so you can see them more clearly under the timing light.

[dingusboy]

Got that. Hooking up the timing light is easy. I need to know how the actual adjustment is done. What part of the dist. do you twist? Does the mechanical timing need to be checked with an add-on tach? How is it done?

[joe_padavano]

Originally Posted by dingusboy

Got that. Hooking up the timing light is easy. I need to know how the actual adjustment is done. What part of the dist. do you twist? Does the mechanical timing need to be checked with an add-on tach? How is it done?

There are three timing settings of concern, initial timing, vacuum advance curve, and mechanical advance curve.

Initial timing is what you read on the balancer with a timing light at idle. You need to have the idle speed set correctly and the vac advance hose disconnected from the distributor and plugged on the engine side of the hose. There is a bolt holding a clamp at the base of the distributor where it goes into the block. Loosen the bolt and you can rotate the entire distributor (note that the aluminum distributor housing sometimes gets stuck in the cast iron block due to galvanic corrosion). Moving the distributor slightly while you watch the timing marks with the timing light will cause the initial timing to move. Since the Olds distributor rotates CCW, turing the distributor body CW will advance timing, turning CW will retard timing. When you get it set correctly, tighten the clamp bolt and recheck to be sure it hasn't moved. Reconnect the vac advance hose and you're done.

Vacuum advance and mechanical advance are curves that can be adjusted with some work. Usually they are set at the factory and for stock engines do not need to be altered. Modified engines may want them changed. Checking either requires a tach or vacuum source, a degreed balancer, and a timing light. You need to map the advance in degrees (as measured at the balancer) against various RPM points to plot the mechanical advance curve. Similarly, plot advance vs. vacuum for the vac advance curve. Stock vac advance cans are not adjustable but adjustable ones are available from the aftermarket. Mechanical advance is changed by swapping the advance weights and springs under the rotor inside the distributor. Again, aftermarket weight and spring kits are available.

Today, this equipment has been replaced by totally electronic advance systems. The Olds 307 uses a distributor with a fixed timing and the computer controls the advance curve based on RPM, throttle position, manifold vacuum, and (for the 1990 cars) a knock sensor. There are aftermarket systems available to do this, and you can change the advance curves with a laptop instead of getting your hands dirty.

[Oldsguy]

Dis-connect vacuum to the advance canister on the distributor and plug the open line with a screw that will fit tightly in the vacuum hose end. Hook up timing light, start car, and read timing. To adjust it you have to loosen the hold down clamp just enough so you can turn the whole distributor by grasping it with your hand. I usually grab it by the top where all the plug wires are but if they are old, cracked or leaky a person could get shocked so some people grab the distributor by the metal base. Don't loosen that bolt on the hold down clamp too much, maybe two turns at the most. Sometimes the distributor is a little sticky because of friction with the block, there is an o-ring on the shaft that is suppose to seal well but it could be dried or stuck a little but it should break loose with a little squirt of light oil around the area where the shaft meets the block. While turning the distributor the mark should move up or down in relationship to the block marker. Up is advance, down is retard. Good luck and hope this helps.
edit: Well, there I go again being redundant. I take too long to compose my posts.....

[joe_padavano]

Originally Posted by Oldsguy

edit: Well, there I go again being redundant. I take too long to compose my posts.....

Beat ya by two whole minutes...

[dingusboy]

Thanks! I appreciate your guidance. I've got a good idea swimming in my head of what I need to do. Once I feel confident with adjusting the timing...on to the Pertronix dist.

[wmachine]

One last thing.
They make distributor specific wrenches to curve around to access the bolt. But Olds engines are nice, because all you need is a 3/8" drive socket set. Use a ratchet, one long (6") extension, and one short (3") extension. That will put the handle above the top of the distributor, and there is enough articulation in the connections to make that "inward curve" to get the socket on the bolt head. Much easier and faster than even a correct distributor wrench!

[dingusboy]

Thanks wmachine.

[Bluevista]

The best instructions on the net would be a place or person that sells your year and model Olds chassis service manuals and buy one.
It'll learn you in easy to understand terms how to use a timing light and change a distributor/engine.

Back in the day I knew a guy who cut a hole in his firewall to adjust the timing while driving/street racing. "Dial advance???...I don't need no stinkin' dial advance."

[jensenracing77]

you will most likely be fine but keep in the back of your mind that if the car is running good and don't run good after you adjusted the timing that the Rubber part of the damper (the part that has the mark) may have slipped. if this happens let us know and we will give more details. the older these cars get the more often i see this.

[jensenracing77]

if i just confused you, just ignore what i just said.

[Yellowstatue]

For plugging hoses I use a golf tee for the smaller sizes, I found that a screw (threaded stuff) doesn't quite seal well enough for me...